The present invention relates to observatory domes for astronomical observatories, space satellite tracking stations, and other similar astronomical purposes. More particularly, the invention relates to a split-sphere observatory dome having a fixed shutter.
Observatory domes which are adapted to be utilized for astronomical purposes are generally of a hemispherical configuration provided with an aperture of generally rectangular configuration running longitudinally from the area of the apex of the dome (zenith or vertical axis) downwardly to the vicinity of the equatorial region of the dome (horizontal axis) so as to facilitate the aiming or sighting of a telescope or the like therethrough.
A dome of the nature described is generally provided with a weather-tight shutter assembly adapted to permit selective opening or closing of the sighting aperture. The shutters utilized are normally fabricated from sheet metal and are characterized by generally elongated rectangular longitudinally curved, or convex configuration and are mounted exteriorly of the dome so as to be adapted to uncover the sighting aperture by upward movement of the shutters on a plane tangentially disposed with respect to the curvature of the dome.
It is important that the telescope and other costly equipment usually housed within such domes be properly protected from the entrance of moisture into the dome. One problem with conventional domes results from the fact that under present practice the shutters do not provide a completely water-tight closure in the normal closed position. Thus, water enters the interior of the dome and thereby causes considerable damage to the instruments within the dome.
Conventional observatory domes of the type described above suffer from a number of other problems which are primarily attributable to the use of shutters as described above. In particular, in conventional observatory domes large openings are not possible without limiting horizon viewing with conventional shutters and wind screens. Moreover, the concentric protrusions common to conventional shutter design increase wind load and cavitational icing. Further, conventional domes require massive arch girders and eccentric ring girders to resist bending and spreading of the slot. Finally, the provision of moveable shutters hinders the weather resistance of the dome as discussed above.
A different form of dome design is employed in the French Observatory Pic-du-Midi. The French design involves a split-sphere observatory dome comprising a spherical rotor provided with a circular aperture or oculus and rotatably mounted in a semi-spherical antrum that has a tilted axis. In the French observatory, the oculus is closed by a double hatched door. This structure is adapted to accommodate only small telescope apertures because of the limited size of the doors. Further, the provision of moveable doors results in some of the same problems experienced in conventional observatory domes.
It is therefore an object of the present invention to obviate the disadvantages experienced in conventional observatory domes. More specifically, it is the object of the present invention to provide a fixed shutter construction for use in a split-sphere observatory dome. It is a further object of the present invention to provide a fixed-shutter construction which improves the weather resistance of the dome. Finally, it is an object of the present invention to provide a means for supporting the rotor shell of a split-sphere observatory dome.